Among currently known food yeast employed as a man's additional foodstuff there are beer yeast and pressed baker yeast. These are saccharomycetes ("sugar fungi") capable of initiating an intensive alcoholic fermentation.
Pressed baker yeast cannot be obtained in amounts sufficient for use thereof as food yeast. There is usually a certain shortage of the yeast to satisfy the demand in their direct application--manufacture of yeast flour products. Furthermore, the yeast contain only minor amount of vitamin B.sub.1 which is vitally important in human metabolism. Thus, pressed baker yeast contain in one gram of dry solids only about 1 microgram of vitamin B.sub.1, very rarely--up to 10 .mu.g; beer yeast--up to 200 .mu.g/g of dry solids.
Employed for nutrition purposes are liquid and dry beer yeast. The resources of beer yeast for food purposes are rather scarce. The reason is that in the manufacture of beer the amount of yeast accumulation upon fermentation of malt must is consumed for the next cycle of fermentation and so on until they lose their force and become enriched with contaminating lactic-acid bacteria undesirable for brewing. Employed for the food purposes are waste yeast with a certain amount of weakened and autolyzable yeast cells. In addition, they contain a small amount of lactic-acid bacteria equally useful. Therefore, the liquid portion contains a certain, and in some cases even considerable, amount of physiologically active compounds. However, totally viable yeast cells, due to a very dense shell thereof, cannot be cleaved in a human stomach and pass through the intestine in their unchanged form.
Known in the art is a process for producing a food vitamin concentrate from beer yeast by carrying out autolysis thereof. The autolysis is preceded by a treatment (washing) of yeast with an alkali solution to eliminate bitter taste. A separator is employed for separation of the residue. The autolysis is conducted at a temperature of from 45.degree. to 50.degree. C. The best results in the yield of nitrogen-containing matters are obtained at the autolysis temperature of 45.degree. C. The resulting autolysate is subjected to a further heating to a temperature of 80.degree. C. Then the autolysate is exempted from cell shells by means of a separator. The resulting transparent autolysate is additionally filtered through a bacterial laminar filter to remove occasional bacteria present in the filtrate. The concentration is conducted in a centrifugal thin-layer evaporator. The required temperature and pressure are determined on the basis of retention of thiamine in the autolysate upon thickening thereof. The final stage, i.e. drying, is conducted at a temperature of 80.degree. C. by means of spraying. In this process losses of thiamine vary from 10 to 20%. The final product has a pleasant odour and contains amino acids in the amount of 480 mg/g. (E. Pajunen, E. Pessa, M. Linko. Production of yeast extract from waste brewery yeast. Third Intern. Specialized Sympos. on Yeasts. Proceedings. Otaniemi-Helsinki. Finland, 1973, Part I, Abstracts, p.91).
This process requires a great amount of the starting feedstock, i.e. brewery yeast, scarcity of which yeast hinders the industrial production of a vitamin concentrate on their basis. The category of alimentary or food yeast should be also exemplified by wine yeast in the production of dry wines.
The production of a food vitamin concentrate from wine yeast resulting from the production of dry wines is novel and hitherto unknown from the literature.